#include<iostream>
using namespace std;

class Solution
{
public:
    int waysToStep(int n)
    {
        if (n == 0) return 0;
        if (n == 1) return 1;
        if (n == 2) return 2;
        if (n == 3) return 4;
        long long dp[61 + 1];
        dp[0] = 0, dp[1] = 1, dp[2] = 2, dp[3] = 4;

        for (int i = 4; i <= n; i++)
        {
            dp[i] = ((dp[i - 3] + dp[i - 2]) % 1000000007 + dp[i - 1]) % 1000000007;
        }
        return dp[n];
    }
};

int main()
{
    Solution s;
    cout<<s.waysToStep(61);
    return 0;
}